Sensorless Force/Position Control of a Single-Acting Actuator Applied to Compliant Object Interaction

This paper deals with a sensorless control approach of a lightweight electric actuator. Force and motion control are necessary to perform manipulation tasks with object interaction of different stiffnesses. The controller must ensure stability in a wide range of rigidity, particularly in soft contact cases. The approach proposed here is based on a force/position control scheme. First, a nonlinear position controller is performed through a linear parameter-varying state feedback. A state observer is added to estimate unmeasurable variables coming from an absence of terminal sensors. Subsequently, an output feedback force control is determined using an H_∞ framework. The controller is experimentally applied on a single-acting actuator to demonstrate the efficiency of this approach dedicated to compliant object interaction.